Dye composition



Pas es Feb. 1a, 1926.

f stair-an STATES,

EDWARD J. WALL, or woLLAs'roN. AND DANIEL r. coms'rocx, or BOSTON, uassacnu- PATENT OIFTFICE.

SETTS, ASSIGNORS TO KALHUS, COMSTOCK 86 WESCOTT, F BOSTON, MASSACHU- SETTS, A CORPORATION OF MASSACHUSETTS. v

' DYE COMPOSITION.

1% Drawing. Application flledluly s, 1917, Serial m 179,050. Benewed'September 12, 1923.

To all whom it mayconcem." Be it known that we, EDWARD WALL, a citizen of the United States, and resident of Wollaston," in the State of Massachusetts, 5 and mam. F. Coms'roox, a citizen of the United States, "and resident of Boston, in the State of Massachusetts, respectively, have invented new and useful Improvements in Dye Composition, of which the following 1 is a specification.

This invention relates to dye composltions and more particularly to dye solutions for sensitizing photographic substances such as silver emulsions. Many organic dyes are employed in the photographic art forrendering silver and other emulsions sensitive to light of various colors or hues. Among the more prominent of these dyes may be mentioned, by way of Bi? example, the isocyanine group, and such individual dyes as ethyl red (quinaldinquinolin ethyl cyaniniodid), homocol (mixture of an isocyanine dye with quinolin red, Schultz #610, which is the product of re action of one mol. benzotrichlorid on a mixture of one mol. quinaldin and one mol. isoquinolin in the presence of zinc chloride), orthochrome T -tolu uinaldin-E-toluquinolinethylcyanin romi pinac rome (pethoxyquinaldin .p methoxyquinolin-ethyL cyamn bromid), pinachrome violet (1: 1'- diethyl-6 6'-aminocarbocyanin halide or the corres ending dimethyl compound), pinacyanc (product of reaction of formaldehyde followed by alkali, on quinaldinium iodet iylate), pinaverdol (p-toluquinaldin quinohnium meth l-cyanin bromid), dicyanine glproduct 0 reaction of potash and atmosp eric oxygen on alpha-gamma-dimethylquinolinium' salts), etc. The usual method of app] ing these dyes, after the photographic p ates or films have been menu actured,

comprises bathing the lates or films in an aqueous bath into whic has been freshly poured an alcoholic solution of the sensitizing dye or dyes. Small quantities of the dyes diffuse into the film of gelatine or other substance and impart color sensitiveness to the grains of silver emulsion, probably by virtue of the photo-electrical properties of the dyes. v Heretof ore it has been ossible to utilize only a small fraction of t e dye in such a the bath. And owing to the excessive cost of these dyes and the great .diflicu lty of obtaining them some, satisfactory method of prolonging the useful life of the aqueous bath has been greatly desired but, up to the present time, appears to have remained undiscovered.

This premature precipitation of the dye is particularly objectionable where, as is usually the condition,the solution contains a plurality of sensitizing elements mixed in definite proportions to produce a certain color sensit1veness in the photographic emulsion, for under such circumstances the several dyes are precipitated at different rates and the correctproportions of the suspended components of the dyes therefore cannot be maintained. Moreover the precipitated residue, even if recovered in dry form, cannot be used over again by bein redissolved in alcohol without first ing carefully analyzed to determine the proportions of the several dyes. Another reason why bathing solutions have heretofore given great difliculty is that a progressive change a pears to go on in the dye solution even be ore noticeable precipitation begins and it is not possible there-- fore to ,repeat the sensitizing pro'cess'with similar vresults after the lapse of even so short a time as ten minutes. It is therefore practically hopeless to standardize the sen sitizing process with the solutions now known.

The principal object of thepresent invention is to overcome the above mentioned difficulties and to prolong the useful life of dye1 solutions by restraining the coa ation an tion.

This and other objects we have attained by the discovery. that the desired restraining precipitation of the dye from t esoluaction may be effected by adding to the dye solution minute amounts of certain mgredients among which, by way of example, may

be enumerated the following: gelatine, albu- 5 men, water-glass, dextrin, sugar, starch, casein, glycerlne, etc. For example, we have retical considerations:

' water a colliodal solution results.

found that on hundredth of one er cent of gelatine added to the aqueous so ution will prolong the life of the bath from ten to thirty times.

It will be noticed that most of the sub stances mentioned in the preceding paragraph, are of the class of substances known as emulsoids, and indeed we have found that any emulsoid will function in the aforesaid manner to a more or less satisfactory extent, it being understood that the term emulsoid is here employed in its usual scientific sense which may be generally described as follows: Systems consisting of solid particles of microscopic or sub-microscopic size distributed through a liquid are known as suspensions, while those having two liquid phases are known as emulsions; consequently solutions resembling the former are called suspensoids, and the solutions which resemble the latter, particularly in showing markedly high viscosities and in formin gelatinous masses on drying, are call' I emulsoids.

The restraining action resulting from the admixture of the gelatine or other emulsoid we believe to be due to the following theo- The dye substances above enumerated are soluble in alcohol but are insoluble in water; consequently when the alcoholic dye solution is poured into the This colloidal solution is of the class known as suspensoids and the microscopic particles have a strong tendency to coalesce and precipitate under certain conditions as, for example, when an electrolyte is added to the solution. This is robably due to thefact that a given type 0 microscopic articles are all elec trically charged I in e manner, for example negatively, whereas the ions of the electrolyte are oppositely charged, that is positivel The like charges of the negative partlcles cause the particles to repel each other and thereby maintain themselves distributed throughout the solution substantially uniformly instead of massing together and settling to the bottom of the container.

11 the addition of an electrolyte thelelectric charges of the colloidal particles in the solution are at least in part neutralized by the oppositely charged ions of the electrolyte and, as they no longer repel but may even attract one another, they are free to approach each otherand to form larger agwhich settle more or less rapidly.

otographic emulsions contain certain soluble constituents and impurities which rapidly dissolve when the lates orfilms are-bathed in the dye solutions and these impurities have the same effect upon the dye solutions as electrolytes. 4

The restraining action of the gelatine or other emusloid may be explained by the assumption thateac particle of the suspensoidaldye surrounds itself with a layer of the emulsoid and then possesses the electrical properties of the latter.

It is to be understood that the above theoretical explanation is given merely for the purpose of more fully and completely disclosing the nature of the invention and is not to be construed as limitingthe scope of the invention in any way whatsoever.

We claim: 1

l. A composition for treating photographic emulsions comprising a colloidal color sensitizing solution, and a dye rotector for restraining the coagulation o the colloidal dye.

2. A composition for treating graphic emulsions comprising a colloidal color sensitizing solution, and a colloidal substance forrestraining the coagulation of the colloidal dye.

3. A composition for treating photographic emulsions comprising a suspensoidal color sensitizing dye and an emulsoidal dye protector.

4. A composition for treating photographic emulsions comprising a suspensoidal color sensitizing dye, and an emulsoidal element in amount of the order of a small fraction of one per cent for restraining the coagulation of the suspensoidal dye upon association'with the photographic emulsion.

5. A composition for treating photographic emulsions comprising a colloidal color dye solution, and an amount of gelatine of theorder of a small fraction of one er cent for restraining the coagulation o the colloid.

6. A color-sensitizing photographic dye composition comprising an isocyamne dye solution, and a dye protector for restraining the precipitation o the dye.

7. A color-sensitizing photographic dye composition comprising a suspensoidal isocyamne dye, and an emulsoidal dye protector for restraining the precipitation of the solid particles of the suspensoidal dye.

8. A composition for treating photogra hic emulsions com rising a colloidal ingre ient adapted to afiiect the emulsion and a protective ingredient adapted to restrain the coagulation of the colloidal ingredient.

9. A composition for treating photographic emulsions comprising a s'uspensoid adaptedto alter the condition of the elnulsion and a protector adapted to prevent the coagulation of the suspensoid, whereby the suspensoid may be applied to emulsions for abllong period without coagulating apprecia y.

10. A composition for sensitizing photographic emulsions comprising a suspensoidal sensitizer and a protective ingredient adapted to revent the coagulation of the suspensoi al sensitizer in the presence of 'hotographic'emulsions for a long period o time.

. 11. A composition for sensitizing photographic emulsions comprising a colloidal sensitizer and a protective ingredient for restraining the coagulation of the colloidal sensitizer in the presence 'of the photographic emulsion, the protective ingredient constituting less' than one per centv of the I composition.

12. A composition for treating photographic emulsions comprising a color-sensitizing dye, and gelatine. i

13. A composition for treating photographic emulsions comprisin a color-sensitizing dye solution and an lngredient for restraining the precipitation of the dye.

14. A composition for. treating photographic emulsions comprising an ingredient adapted to aflect the sensitivity of the emulsion and an ingredient adapted to control the precipitation ofthe first ingredient.

Signed by us at Boston, Massachusetts, this second day of July, 1917.

V DANIEL F, COMSTOCK.

E. J WALL. 

